Structural heart disease includes many conditions or diseases that may affect the heart muscle itself, the constitution of the heart and the heart valves that control the flow of blood in an out of the heart. Structural heart disorders may already be present at birth or they may develop later in life and can be caused by several conditions. For example, coronary artery diseases may cause blockages of the heart's arteries. It is common to conduct minimal invasive treatment in order to improve the heart condition. For example, insufficiency or stenosis of the heart valves, congestive heart failure and cardiomyopathy may be reduced by invasive treatment. These treatments may include angioplasty and stent placement, surgical repair and replacement of the mitral valve, heart surgery in general and revascularization. In the following it is focused on the minimal invasive treatment of structural heart defects through minimally invasive percutaneous access (e.g. catheterization or needle insertion), which is guided e.g. under C-arm fluoroscopy.
Thereby, a dynamic three-dimensional roadmap provides a live guidance through tortuous vasculature or another pathological anatomical structure in that an overlay of real-time two-dimensional fluoroscopy images and a three-dimensional reconstruction of the vessel tree is achieved. The two-dimensional image may be provided by an X-ray image acquisition device, e.g. of a type called C-arm. As a result, an image shows the advance of a guide wire, a catheter, stents, coils or needles on a single image in real-time and it improves visualization during complex interventions.
In order to match the acquired two-dimensional images with the three-dimensional representation of the dataset, the frame of reference of the X-ray image acquisition device, for example a C-arm X-ray system, and the frame of reference of the three-dimensional multi-modality data set need to be registered. The direct registration to the two-dimensional projective X-ray an image can be performed either manually, or automatically, employing a registration algorithm.
For the various purposes of interventional treatments an optimal direction of view is mandatory. This means, the surgeon or clinician must have the ability to watch each detail needed for a correct application of intracardiac devices or other instruments. Therefore, it is necessary to choose an appropriate viewing angle in order to be able to optimize the view for a clinician during the invasive procedure. It therefore is needed to adjust the X-ray imaging apparatus so that the desired viewing angle can be achieved.
For example, the major vessels of the coronary circulation are the left main coronary that divides into left anterior descending and circumflex branches, and the right main coronary artery. The left and right coronary arteries originate at the base of the aorta from openings called the coronary ostia located behind the aortic valve leaflets. During interventional treatments of the aorta, for example deployment of a stent, the clear visibility of the ostia is mandatory in order to prevent a blockage of the ostia by means of the stent to be deployed.
In U.S. Pat. No. 6,424,731 B1 a method for controlling an X-ray image acquisition device for enabling the device to automatically follow a viewing direction onto a three-dimensional representation of a vessel to be examined in real-time is disclosed. Further, this method allows prevention of collisions with a patient's body in that it allows prediction of geometry parameters that are physically not possible without collision.
Further, in US 2002/0006185 A1 a method for automatic positioning of an X-ray image acquisition device is disclosed, in which a first direction is determined, the viewing direction being calculated so that the image quality will be superior to hat would be obtained with a viewing direction parallel to the first direction.